The invention concerns a wire mesh, a method of manufacturing it, and a device for carrying out the method.
Preferably cylindrical one-piece ceramic units are employed to decontaminate the exhausts from internal-combustion engines. The unit is securely mounted in a housing with a wire mesh between the two components. In the known method of manufacture, the unit is provided with the mesh and the two components are positioned loose in the two-part housing, which is then subjected to pressure to close it. The pulsating stream of exhaust, however, tends to shift the unit back and forth, and attempts have been made to eliminate this motion by the application of radial force in the form of a molded-in bead. These attempts have not been successful because too much pressure while the ceramic unit is being assembled can damage it. Too little pressure on the other hand may not hold the components together securely enough.
Introducing an annular groove into the edge of the end of the separate components (German OS 2 412 863) or positioning a multilayer and accordingly reinforced wire mesh at that location (German OS 3 519 965) to accommodate the axial forces on the unit has accordingly been proposed.
The drawbacks to the catalysts manufactured by the known method derive from the forces that act on the unit not only during assembly but also in operation to prevent the pulsating flow of gas that occurs in internal-combustion engine exhausts from forcing the unit against the housing and damaging it. The drawback of multiply wrapping the unit in order to reinforce its edges as in the second aforementioned method is that the extra layers create a lot of surface pressure at the edge of the unit, which can accordingly be damaged.
The object of the present invention is to propose a wire mesh, a method of manufacturing it, and a device for carrying out the method that will ensure maximum protection of the unit not only while it is being assembled but also while it is in operation.